This article (June 2018) says that feature layers participating in view layers with joins can't have their schema altered.
Is this information still valid?
We've been experiencing this with a hosted feature layer which may need to have changes to some field domains (from the Data tab in the item details page). This means we'll have to delete and recreate the view and the web map each time users ask for a change in a domain. And some extra steps to make apps use the new web map.
The weird thing is that in a test feature layer we were able to change field names and domains in AGOL after creating a view with it using the Join Features tool. I've been unable of reproducing this again but it makes me think there's an exception to this limitation. Am I right?
To my experience and knowledge the article is still valid and I am not aware of an exception to this limitation - I ran through the workflow a couple of times to be sure and my domains and field names in each Hosted Feature Layer participating in the join-created View became non-editable.
That said, if you find a workflow that consistently reproduces the behavior we would definitely want to test it out and log an issue on our end, that would not be expected behavior and could have some serious consequences for the integrity of the View.
Hope that helps,